1. Field of the Invention
The present invention relates to a controller for controlling a liquid pressure for a brake or clutch of a vehicle or general machine.
2. Description of Background Art
The following examples of braking liquid pressure controllers have been known. The first example is disclosed in unexamined Japanese Patent Publication No. HEI 1-266050, wherein a detecting means is provided for electrically detecting an operating stroke amount and a load of a brake lever or brake pedal, and on the basis of a detection signal from the detecting means, an oil pressure control means controls the pressure of a caliper cylinder of a wheel brake. The second example is disclosed in Unexamined Japanese Patent Publication No. SHO 63-64858, wherein a master cylinder is provided for operating a caliper cylinder, and a braking liquid absorber and a liquid pressure generating means are switchably disposed between the master cylinder and the caliper cylinder. The third example is disclosed in Unexamined Japanese Patent Publication Nos. HEI 3-220054 and SHO 62-116346, wherein a liquid pressure generated in a master cylinder is boosted by a hydraulic circuit to be fed to a caliper cylinder upon a normal state, and the liquid pressure can be controlled by a switching means upon traction control and antilock brake control.
In the first example, not only the detecting means but also the oil pressure control means require high reliability. In some cases, a second brake or the like directly connected to an operating lever or the like is required.
In the second example, the mechanism including the braking liquid absorber, liquid pressure generating means and switching means for switching them is complicated. This is disadvantageous in terms of manufacturing cost and mounting space. Moreover, the switching means becomes a continuous operating state upon continuous braking such as upon stoppage. This is disadvantageous in terms of economy.
In the third example, the mechanism is further complicated and is difficult to be reduced in weight, size, and cost.